In minimally-invasive surgical techniques such as endoscopy, thoracoscopy, laparoscopy, pelviscopy, arthroscopy, and the like, elongated instruments are introduced into the body through small incisions or percutaneous cannulae to perform surgical procedures at an internal site, obviating the need for the large incisions characteristic of conventional, open surgical techniques. Visualization is facilitated by the use of specialized devices known as endoscopes, laparoscopes, pelviscopes, thoracoscopes, or arthroscopes, which typically consist of a rigid, elongated tube containing a lens system and, at the proximal end of the tube, an eyepiece or camera mount. The distal end of the tube is introduced into the body through an incision or cannula, and, by looking through the eyepiece, a surgeon may observe the interior of a body cavity. In addition, a small video camera may be attached to the camera mount and connected to a video monitor to provide a video image of the procedure. Usually, such visualization devices further include a light source at the distal end of the tube for illuminating the interior of the body cavity.
As the complexity of the procedures that can be performed by means of minimally-invasive techniques has increased, so has the demand for higher quality visualization systems to facilitate such procedures. For example, in commonly-assigned co-pending application Ser. No. 08/023,778, filed Feb. 22, 1993, the complete disclosure of which is incorporated herein by reference, new techniques are disclosed for performing coronary artery bypass grafting and other thoracic surgical procedures using minimally-invasive techniques. Coronary artery bypass grafting involves the use of microsurgical techniques to create an anastomosis, usually by suturing, between a coronary artery and either an existing artery such as the mammary artery, or a natural or synthetic arterial shunt connected to an upstream arterial blood source. As described in the forementioned patent application, long-handled microsurgical tools may be introduced through small incisions or cannulae positioned in the intercostal spaces of the rib cage to perform the anastomosis. Such procedures may take a team of surgeons up to several hours to complete. These intricate procedures therefore demand a visualization system that produces an extremely high-quality image of very small surgical sites, and that allows multiple surgeons to simultaneously view a surgical site comfortably over long periods of time.
While many of the visualization devices in current use have proven to be effective for use in certain minimally-invasive surgical procedures, such devices are frequently inadequate for the performance of complex microsurgical procedures such as coronary artery bypass grafting. For example, if just an eyepiece is used on an endoscope, only one person can look through the device at any one time, requiring an individual scope introduced through a separate incision or cannula for each person assisting in or observing the procedure. Further problematic is the difficulty in maintaining the eyepiece in alignment with the surgeon's eye for continual visualization while manipulating the instruments necessary to perform the procedure. Additionally, because these visualization devices are typically monoscopic, they have poor resolution of depth of field in comparison to a person's binocular, stereoscopic vision using both eyes.
By mounting a video camera on such visualization devices, more than one person may observe a procedure by watching a video monitor, without the need for additional incisions into the body cavity. However, the miniature video cameras in current use frequently produce sub-optimal image quality in comparison to direct vision through the scope. Further, indirect visualization by means of a video monitor rather than by direct sight is somewhat disorienting, and requires significant training and practice to develop the hand-eye coordination necessary to adeptly perform surgery. Additionally, where multiple surgeons are working in the surgical site under video imaging by a single scope, the video image can be correctly oriented relative to only one of the surgeons at any time. Other surgeons must adjust their actions to compensate for an inverted or otherwise misoriented image. Moreover, because most scopes, video electronics, and video displays in current use are monoscopic, video visualization also fails to provide the depth perception of normal stereoscopic vision.
What is needed, therefore, is a percutaneous visualization system for use in minimally-invasive surgical procedures that facilitates direct, stereoscopic visualization of a body cavity through a small incision or cannula. The visualization system should facilitate hand-eye coordination that is close or equal to that of open surgical procedures. Preferably, the visualization system will have the capability for wide-angle visualization as well as magnification to facilitate the performance of complex microsurgical procedures. Further, the visualization system should allow multiple surgeons to simultaneously view the same surgical site with comfort for long periods of time. The visualization system will preferably be configured for introduction through intercostal spaces of the rib cage for thoracoscopic procedures, but should be useful in any of a variety of minimally-invasive procedures, including laparoscopy, pelviscopy, arthroscopy and the like.